This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-247911, Sep. 1, 1999; and No. 2000-253926, Aug. 24, 2000, the entire contents of which are incorporated by reference.
The present invention relates to an optical member switching apparatus for selecting a desired one of a plurality of optical members in correspondence with the object to be observed, and aligning the selected optical member on an observation optical path in an optical apparatus such as a microscope.
Optical member switching apparatuses include an object lens switching apparatus, i.e., a so-called revolver, which selects an objective lens with a desired magnification in correspondence with the object to be observed, and aligns the selected lens on the observation optical path, a cube switching apparatus which locates a plurality of cubes (filter blocks) at a branch point between the observation optical path and illumination optical path in correspondence with the characteristics of a fluorescence reagent in epi-fluorescence observation, and the like. Conventionally, in an apparatus of this type, rotation of a revolver is stopped by providing a mechanical engaging mechanism between movable and stationary portions of the revolver. The engaging mechanism mechanically engages the movable and stationary portions of the revolver every time the optical axis of each objective lens attached to the revolver reaches a position where it matches the observation optical axis of an optical apparatus such as a microscope or the like, thus aligning and holding the lens.
As a first example of such optical member switching apparatuses, a technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-281457 is known (prior art 1). This objective lens switching apparatus has a revolver 102 to which a plurality of objective lenses 101 are attached, a motor 103 for rotating and braking the revolver 102, and a transmission mechanism 104 for transmitting the rotation of the motor 103 to the revolver 102, as shown in FIG. 1. A mark plate 105 which has two index portions that give the deceleration and stop timings of the motor 103 is provided to the rotation shaft of the motor 103 or transmission mechanism 104, and a reflection sensor 106 and transmission sensor 107 corresponding to the two indices are provided to an apparatus stationary portion 109. A click ball 108 is fixed to the upper surface on the outer periphery of the revolver 102, and a desired objective lens 101 is aligned to an observation optical axis m when the click ball 108 engages with a distal end hole (not shown) of a leaf spring 111 fixed to a stationary member 110 in which the revolver 102 pivotally fits.
The motor 103 begins to decelerate when the desired objective lens 101 has reached a given position before the observation optical axis m. After the motor 103 has sufficiently been decelerated, it is stopped when the lens 101 has reached a position near the position of the observation optical axis m. At this time, the reflection sensor 106 detects a reflection pattern of the mark plate 105 before the click ball 108 falls within the engaging range of the distal end hole (not shown) of the leaf spring 111 biased by an elastic force, and an electronic control circuit sufficiently decelerates the rotation of the motor 103 in response to this detection signal. When the click ball 108 falls within the engaging range of the leaf spring 111, the transmission sensor 107 detects a notched portion of the mark plate 105, and the electronic control circuit completely stops the motor 103 in response to this detection signal. As a result, the click ball 108 fits in the engaging range of the distal end hole of the leaf spring 111, and the desired objective lens 101 is aligned to the observation optical axis m. In this way, the objective lens can be accurately and quickly aligned to the optical axis of the optical apparatus.
As a second example of the optical member switching apparatus, a technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 7-311343 is known (prior art 2). This objective lens switching apparatus has a revolver 112 for holding an objective lens (not shown), a motor 113 for rotating and braking the revolver 112, an alignment portion 114 for mechanically stopping the revolver 112 decelerated by braking the motor 113 at a predetermined position, and a constant amount rotation detector 116 for detecting a predetermined amount of rotation of the revolver 112, as shown in FIGS. 2 and 3. The revolver control circuit 115 begins to brake the motor 113 a pre-set delay time after it receives the detection result from the constant amount rotation detector 116.
The braking timing of the motor 113 for aligning a desired objective lens to the observation optical axis is adjusted by an electrical means. As the detection means 116 that detects a predetermined amount of rotation after the revolver 112 begins to rotate, for example, a photointerrupter 117 and light-shielding plate 118 are provided, and the photointerrupter 117 detects a notch 118a of the light-shielding plate 118, thus generating a detection output. The revolver control circuit 115 generates a delay output the pre-set delay time after it receives the detection output, and brakes the motor 113 at that timing. Since adjustment for accurately aligning a desired objective lens can be done by electrical delay time adjustment, the adjustment process can be facilitated.
Furthermore, as a third example of the optical member switching apparatus, a technique disclosed in Japanese Patent No. 2,539,903 (Leica) is known (prior art 3). This objective lens switching apparatus has a motor driving device 122 for rotating a revolver, a code device 123 for detecting the rotation position of the revolver, a selection means 124 for pre-selecting a revolver hole as a target position, a control circuit 125 for controlling rotation of the motor driving device 122, and an engaging means (not shown) for fixing the selected revolver hole at the target position, as shown in FIG. 4. Deceleration marks 128 which are used to begin to brake the revolver and correspond in number to that of objective lenses are formed on a code disk 127 of the code device 123, and the rotational speed of the motor driving device 122 is decreased by collaboration of the deceleration marks 128 and a sensor 129 before the revolver reaches the target position, thus accurately and quickly aligning a desired objective lens to the target position.
These prior arts suffer the following problems. That is, in any prior art mentioned above, since the way objective lenses are attached (the number, types, and attachment positions of lenses) varies depending on apparatus users, and the load on the motor that rotates the revolver changes, it is difficult to attain optimal stop control of the motor.
In prior art 1, as shown in FIG. 1, the positional relationship between the reflection sensor 106 and the reflection pattern of the mark plate 105, and that between the transmission sensor 107 and the notch of the mark plate 105 are accurately adjusted in assembly, and are optimized to allow successful engagement between the click ball 108 and the leaf spring 111. However, in this prior art, since the mark plate 105 having two indices that give the deceleration and stop timings of the motor 103 are provided not to the revolver 1102 but to the rotation shaft of the motor 103 or transmission mechanism 104, if clattering (backlash) of the transmission mechanism 104 is large or varies in units of objective lens switching apparatuses, it is hard to adjust the positional relationships between the sensors 106 and 107 and the mark plate 105.
Also, since both the reflection sensor 106 and transmission sensor 107 must be accurately adjusted, a long adjustment time is required. Furthermore, the load inertia on the motor 103 largely varies depending on the manner objective lenses are attached (the types, number, attached positions, and the like of lenses). However, the positional relationship adjustment is always fixed irrespective of the manner the objective lenses 101 are attached, and it is very difficult to adjust the positional relationships between the mark plate 105 and the sensors 106 and 107 to assure engagement between the click ball 108 and leaf spring 111 without any overrun or shortrun of the revolver 102 in every cases.
In prior art 2, as shown in FIG. 2, the delay time is optimally adjusted in units of revolver devices to prevent a click ball 119 from overshooting or undershooting a V-groove 120. However, since this delay time is a fixed value for each revolver device, and cannot cope with a change in the manner objective lenses are attached (the types, number, and attached positions of lenses), the click ball 119 often fails to engage with the V-groove 120 depending on the manner these objective lenses are attached. Also, such shortcomings readily occur when the load on the motor 113 (see FIG. 3) or the motor characteristics themselves change due to aging of a revolver device.
In prior art 3, as shown in FIG. 4, the deceleration marks 128, which are used to start braking of the revolver 121 and correspond to the number of objective lenses, are formed on the code disk 127 to have optimal sizes so as to accurately and quickly align a desired objective lens to the target position. However, this prior art cannot satisfactorily cope with changes in ways objective lenses are attached or aging, either.
As a problem common to prior arts 1 to 3, since the rotation position is electrically detected and the motor is braked to align the lens, difficult adjustment and complicated control means are required, and changes in the manner optical members are attached cannot be coped with.
The present invention has been made in consideration of the conventional problems, and has as its object to provide an optical member switching apparatus which can easily adjust the positional relationship by a simple means, can cope with changes in the manner optical members are attached, and can reliably switch optical members.
In order to achieve the above object, according to the first invention, an optical member switching apparatus for electomotively switching a plurality of optical members, is characterized by comprising intermittent operation transmission means for intermittently making power transmission between a motor driving source and a switching member to which the optical members are attached, alignment means for aligning at least one of the plurality of optical members on an optical path during a pause period of power transmission by the intermittent operation transmission means, and detection means for detecting if at least one of the plurality of optical members is aligned on the optical path by the alignment means.
In such optical member switching apparatus, the driving power of the motor driving source is converted into the intermittent detection operation of the switching member to which the optical members are attached, the alignment means accurately aligns a given optical member on the optical path, and the detection means confirms the alignment result of the optical member.
According to the second invention of the present invention, the apparatus of the first invention is characterized that the intermittent operation transmission means has a motor gear provided to the motor driving source, a spur gear which meshes with the motor gear, a driving wheel which is formed integrally with the spur gear, and has a transmission pause portion for pausing power transmission from the motor driving source, and a power transmission portion for transmitting power from the motor driving source, a small gear which meshes with a large gear of the switching member, and a driven wheel which is formed integrally with the small gear, and has a slave transmission pause portion for pausing power transmission from the driving wheel, and a power transmission portion for transmitting power from the driving wheel, and a rotation amount of the slave transmission pause portion defined by a gap between the slave transmission pause portion and the transmission pause portion is smaller than a pull-in amount of the alignment means in a rotation direction thereof.
According to such optical member switching apparatus, since the rotation amount of the slave transmission pause portion defined by the gap between the slave transmission pause portion and he transmission pause portion is set to be smaller than the pull-in amount (click groove width) of the alignment means in its rotation direction, the optical member can be reliably aligned onto the optical path during the power transmission pause period of the intermittent operation transmission means.
Furthermore, according to the third invention of the present invention, the apparatus of the second invention is characterized that the slave transmission pause portion is a pigeon tail shaped stationary portion formed on an outer periphery of the driven wheel, the slave power transmission portion is a toothed groove having epicycloidally approximated gear teeth, which is formed on the outer periphery of the driven wheel and on a portion other than the pigeon tail shaped stationary portion, the transmission pause portion is a stationary portion which engages with the stationary portion of the driven wheel, and the power transmission portion is an engaging pin which engages with the toothed groove of the driven wheel and the number of which is equal to the number of toothed groove.
According to the present invention, since the power transmission period uses a toothed groove having epicycloidally approximated gear teeth, smooth power transmission is assured. In a transmission pause period falling outside the power transmission period, nearly no load is imposed on the motor driving source, and a variation of the motor driving source due to the load is smaller than that in the conventional sensor detection scheme. Also, since one pause period is formed per revolution, the present invention can be applied to apparatuses having different numbers of holes by changing only the gear ratio between the switching member and driven wheel.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.